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doi:10.2204/iodp.proc.342.203.2017

Introduction

A major aim of Integrated Ocean Drilling Program Expedition 342 was to obtain expanded Eocene sequences in clay-rich drift deposits from the North Atlantic (see the “Expedition 342 summary” chapter [Norris et al., 2014a]). Remarkably, Expedition 342 managed to recover Eocene-age deposits in eight sites on the J-Anomaly and Southeast Newfoundland Ridges, thereby providing (near-) continuous coverage through the entirety of the epoch along a cross-site megasplice. Three sites included in the megasplice (Southeast Newfoundland Ridge Sites U1408, U1410, and U1411) are clay-rich drift deposits in the middle Eocene (Sites U1408 and U1410) and across the Eocene/Oligocene transition (EOT) (Site U1411). The temporally expanded sequences and excellent carbonate preservation afforded by the clay-rich drift intervals and the high North Atlantic latitude of all sites drilled during the expedition (39°56′–41°37′N) provide an exceptional opportunity for resolving outstanding questions of Eocene paleoceanography.

Capitalizing on the exceptional coverage of Eocene strata, the initial goal was to generate continuous geochemical and physical property data sets and tuned age models necessary for subsequent investigations. To this end, efforts were initiated to develop X-ray fluorescence (XRF) records at 10 kV as needed for splice refinements and development of an anchored astrochronological timescale for the Eocene and a continuous stable isotopic stack from benthic foraminiferal calcite (e.g., δ¹⁸O and δ¹³C). To achieve the latter goal, the Eocene Stable Isotope Consortium (ESIC) was established, uniting 10 participating laboratories and more than 20 individuals from around the world. It is the preliminary results of this collaboration that we report here.

ESIC sampling occurred along an Eocene megasplice from Site U1411 (EOT; drift deposit; current water depth = 3300 m) to Site U1406 (EOT to late Eocene, pelagic sedimentation; current water depth = 3800 m) to Site U1408 (middle Eocene; drift sedimentation; current water depth = 3022 m) to Site U1409 (primarily early Eocene; pelagic sedimentation; current water depth = 3500 m). All sites are located on the Southeast Newfoundland Ridge, with the exception of Site U1406 (see Table T2 in the “Expedition 342 summary” chapter [Norris et al., 2014a] for site details). Here we present the weight percent coarse fraction (wt% CF) records from the ESIC samples prepared to date. Weight percent CF records the relative amount of sediment greater than 63 µm in size; in the deep sea this is the size fraction typically comprising foraminifers. These 8674 samples, 80% of the consortium total, already make this record the highest resolution (and longest) sequence of wt% CF data from the Eocene and provide additional insight into the paleoceanographic evolution in the North Atlantic.

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